1. Related Applications
This application claims priority from British Application No. GB 9016768.5 filed 31 July 1990 and assigned to the same assignee, Eaton Corporation, as this application.
2. Field of the Invention
The present invention relates to a gear shaft for a transmission, on which shaft at least two gears are to be carried. In particular, the present invention relates to a gear shaft carrying at least a first and a second gear wherein the first gear is formed on the shaft from the material of the shaft, often because the diameter of the gear is small enough not to allow radially intermediate splines or other mounting devices, and subsequent gears are desired to be removable, and have a larger diameter which allows the intermediary of splines.
3. Description of the Prior Art
Gear shafts for transmissions carrying two or more gears fixed for rotation therewith are well known in the prior art as may be seen by reference to the countershafts illustrated in U.S. Pat. Nos. 3,105,395 and 4,754,665, the disclosures of which are hereby incorporated by reference.
Transmission gear shafts carrying one or more first gears formed integrally therewith (often in the form of involute spline/gear teeth) and one or more non-integral second gears permanently or detachably fixed to the shaft for rotation therewith are also known in the prior art as may be seen by reference to U.S. Pat. Nos. 4,432,251; 4,735,109; 4,375,172 and RE 32,591, the disclosures of which are incorporated herein by reference.
These prior art structures were not totally satisfactory as, if the first gear, or gears, and the splines for the second gear, or gears, are individually formed on a shaft, they require different machines, e.g. transfer from one machine to another, realignments and other such time-consuming steps and complications. Moreover, each tool requires an axial run-out length, so that an axial length of the shaft between the gears cannot be used and space and material are wasted. If the spline or splines are replaced by one or more longitudinal keyway(s) with a body inserted therein to form a projection, similar problems of transfers, realignments and loss of some axial length, are encountered.
Also, if the second gear or gears are welded on the shaft, while there is not so much machine tool run-out, these latter gears may still be circumferentially misaligned with the first gear, and furthermore none of these second gears is removable.